How to populate a Grails domain class with a List<Double>

Question

I have to create a Application with Grails 4. For now, there is no database, it's all in memory.

All I want, is that a Module can hold a list of doubles which represent the grades.

The domain class Module.groovy:

package myapp

import grails.rest.Resource

@Resource(uri='/module', formats = ['json', 'xml'])
class Module {
    String title
    String description
    int semesterID
    List<Double> grades;
    double finalGrade


    static constraints = {
        title blank:false
        description blank:false
        semesterID blank:false
    }
}

To develop the app, I'd like to work with a populated object. So I initialize a few in BootStrap.groovy:

class BootStrap {

    def init = { servletContext ->
        //Create default Modules
        new Module(title: "WebeC", description: "Web Engineering", semesterID: 1).save()
        new Module(title: "WebeC", description: "Web Engineering", semesterID: 2).save()
        new Module(title: "ism", description: "Information Security Management", semesterID: 2).save()
    }
    def destroy = {
    }
}

So far so good, but I fail when I try to populate the grades. Things I already tried: (all in BootStrap.groovy)

//test 1
 new Module(title: "WebeC", description: "Web Engineering", semesterID: 1, grades: [4.0, 5.5, 3]).save()

//test 2
new Module(title: "WebeC", description: "Web Engineering", semesterID: 1, grades: {[4, 5, 6]}).save()

// test 3
 def List<Double> temp = [4.0, 5.5, 3]
 new Module(title: "WebeC", description: "Web Engineering", semesterID: 1, grades: temp).save()

The output is always the same:

[{"id":1,"title":"WebeC","semesterID":1,"grades":[],"description":"Web Engineering","finalGrade":0.0}, ...]

Is it just a syntax problem or is my whole approach wrong? Thank you very much

Answer 1

The answer from Andriy Budzinksyy was correct. To work with the REST Api anohter file was missing under views:

model{
    Module module
}

json g.render(module, [expand: ['grades'], resolveTemplate: false])

I also slightly changed BootStrap.groovy:

  new Module(title: "WebeC", description: "Web Engineering", semesterID: 1, grades: [4.0, 5.5, 3] ).save(flush: true)